Anode construction



Dec. 6, 1949 M. J. zUNlcK 2,490,246

ANODE CONSTRUCTION Filed NOV. l5, 1945 INVENTOR.

Patented Dec. 6, 1949 UNITED STATES ANoDE CONSTRUCTION Michael J. Zunick, Chicago, Ill., assigner to General Electric X-Ray Corporation, Chicago, Ill., a corporation of New York Application November 13, 1945, Serial No. 628,302 1 claim. (ci. 25o-149) The present invention relates in general to electronics and has more particular reference to an anode structure for X-ray generators.

An important object of the present invention resides in providing an improved anode having a target surface of metal, such as germanium, rthat is r-eadily soluble with other metals and hence difficultly mountable, in substantially pure uncontaminated condition on target supporting means comprising such other materials; a further object being to mount a readily soluble metal on a support while maintaining :the supported metal in substantially pure and uncontaminated condition.

Another important object is to provide an anode target of readily soluble metal, such as germanium, in substantially pure condition without contamination by other metals in solution therein, to thereby provide an X-ray generating target of pure metal for the generation of X-rays of a character particularly well suited for the analysis of other materials by X-ray diffraction.

Another important object is to :provide an X-ray tube particularly adapted for the analysis of materials by diffraction, the tube having an' X-ray generating target of substantially pure metallic germanium, or other readily soluble metal.

Another important object is to form a target of substantially pure metal by solidifying a mass Ilof readily soluble metal, such as germanium, from its molten state, in place, in a formed pocket in a target support of metal, such as copper, iron, nickel and the like, readily soluble with the target material in molten condition, while maintaining the target material against contamination by such soluble metals; a further object being to apply the target material in molten condition, in a pocket lined with metal, such as molybdenum, tungsten, tantalum and the like, that is not readily soluble with the target material, ywhereby to maintain the same in substantially pure condition during and after solidication thereof in the pocket. f

- The foregoing and numerous other important objects, advantages and inherent `functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection Iwith the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

. Fig. 1 is Ia partially sectionalized side View :of an X-ray tube embodying the present invention; and

Fig. 2 is an enlarged, partially sectionalized side view of the anode embodied in the device shown in Fig. 1.

' X-ray diffraction analysis of test materials may be accomplished by exposing the material to be analyzed sto X-rays while observing the X-ray diiraction characteristics of the material on an X-ray sensitive screen or film.

The spectral characteristics of X-rays generlated by electron impingement on a suitable target depend upon the material Iforming the target in the X-ray generator, every target material having its own characteristic spectrum, which is independent of the operating potential of ftheV generator above a minimum voltage, which minimum voltage is also characteristic of the target material. Any target material may, of course,

be employed for X-ray diilraction analysis pro-A viding that the material of the target, and hence its spectral characteristics, be known, as other-'- wise spectral lines caused, by the target mate-- rial, in a spectrograph of the material being examined may be mistaken for lines supposedly caused by the material underexamination.

The choice of la proper target material for diffraction analysis depends upon the type `:of specimen being examined, the examination tech'- nically employed, and the kind of information sought. It is obvious, however, that a prerequisite for accurate analysis is accurate knowledge` of the spectral characteristics of the target atA whichthe X-rays, used for diffraction analysis, are generated. It is, therefore, desirable to provide generators having targets of pure metal,vin order to insure that the spectrum of the gene erator will have only the known characteristics of the target material employed and to avoid the inclusion in the spectrum of unwanted lines imparted by the presence of contaminating metals'.

Germanium is a metal well suited for use as an" X-ray generating target for producing X-rays for diffraction analysis, Germanium, however,` together with other suitable metals, is readily soluble with most materials, such as copper, iron, nickel and the'like, which may be conveniently employed for target supporting purposes in X-ray tubes, the choice of materials for such purpose being limited mainly by cost considerations; and it is the purpose 'of the present invention tofprovide practical,` yet inexpensive means for mounting germanium and other readily contaminated' metals' onv supports of material readily soluble therewith while preventing contamination of the target material by unwanted dispersion of the material of the support in the mounted metallictarget.

To illustrate the invention, the drawings show an X-ray tube Il comprising an anode l2 and a cathode i3 in facing' relationship within an hermetically sealed and evacuated envelope I4, suit' able electrical connections being provided forelectrically energizing the anode and cathode for' X-ray generation from a suitable external power source, or sources.

:The cathode I3 may, comprise a head l5 supported and sealed upon a re-entrant envelope portion comprisingv a hollow stem I6, Conductors for energizingthe. electron emitting filament I 1..' of the cathode may extend through thestem I6. The cathode end of the tube may be fitted with a suitable base I8 for connecting the conductors^ with a suitable external power source for-'energizing the filament I'I for electron emission. The cathode comprises means for;generating'ancl` di recting electrons upon the facing orrtargetv end,A 1 0;

I9 of the anode, whereby to generate X-rays as a result of electron impingementfon theftarget:

The anode, near its target remote end, vmay be secured to a sealing disc or washer 2Il havingi= an annular edge forming a glass-to-metal seal 2'1 with the re-entrant portion 22of`theenvelope;. the anode having an extension projecting` out-` wardly through the disc 20.v4 and being ttedwithl. inlet 'and'outletconduits for. the circulation of a cooling iiuid intothe anode adjacent the target' endthereof for cooling the same. Theen velpe 'I4 preferably, though not essentially, comprises lead4T glass and-is' formed with conicaleme bossments=-fitted-with windowpanes 23"of beryl lium; orother'suitable Xlray transmittin'g'matee rial, thewindoW-panes beingk located on the :en-- velope oppositethe target end ofthe anode in position to--project'X-'rays from the targetoutfwardly 'of-'the=envelope; The cathode head' may be provided.` with afskirt 24 encircling the target. end'of theanode and formedwith openings in linev withth'esaidwindow panes for the trans` mission: of useful X-'ray` beams from. the4 anode' to andithrough the-window'panes. The tube=is1 also preferably' enclosed'iin an. annular sleeve 25; which may comprisey split" parts'A suitablyf clampedtogether around 'the window portion' of z the envelope, the sleeve being provided-with 'onen' ings foi-'receiving therwindow'; carrying. emlciossments:y Ifk desired; the sleeve 25:,may'be formed oFmaterial'opaque-to Xra,ysV for the` purpose of coni'ning therein all X-rays exceptv the -beams ernananting` from the anode-and traveling'through' the openings-tin the= cath'odefskirtZII and 'thence'- throughthezwindow-panes 231.

The anode- IZI comprises ai' metallic bases 26" whielrfrnayfbez madeafofany -suitable or preferredl material,v suchasl copper, iron, nickel and the like;r Ther base -isformad with. a target: carryer ingend 21T havinga surface facingv the. cathode, saidfendportion, inaccordance=-with the pres; ent: invention, being formedwith a: cavity 28 which islined` with. a cup-shapedv insert'.` 29-A off' tantalum. tungsten. molybdenum` orf other mate;A rialdiffcultly soluble'with germanium.

Thel lining' 29 may bell applied b vecasting the* same'; in place; in therbaseaportion'ZT'during'the formation-l oi' the.` base. Ordinarily the:r b'a'se-A is formedr asv-a* casting operation* ina. suitable die.v irrwhiclriv the.: preformed liningh cup; 29" may-be? mounted; astA arr; insert andA the'fvmaterial. of thea' basefcast. intothe-diezupcn and' around :the: cupi: 29E: 'Iheernaterial ofr the:4 basefis'- sufii'ciently. sole ble withf. the-ematerial 1 of! thecupvzV `2 9:,to1rwetthei-- Saime-andzithusrsecure" thee?cupfilrmlyF initi'etfend; of the base portion 21.

After;l the'flzracse` has `ithusr `been frmedr'lwith-:the cup^29 ii'n .place therein. therselected anode ima: teria1, such: as germanium-,- in 4molten condition; mayf'bef poured` intoV the 'cup' and allowed to.so1id'.v ifyf to, form `a metallic target` button 39' of: metal: in.l substantially pure :condition without.' contami-r ination Y Iby .anyfmetal dissolved therein'.. Tanta-- lum, tungsten and molybdenum arefmaterialsf relatively diicultly "suiubleirrmnltengermam'um tuV 4 which, however, will wet the material of the cup suciently to result in a rm anchorage and integration offzthe target material with the:A material of thel cup 29, to hold the-targetbutton 30 in place after the molten material has solidified.

After solidication of the button 30, the cathode facing target surface I9 of the anode may be ground, polished or otherwise finished toprovide a smooth' unbroken target surface, the-central portionsfof which comprise the pure metal'surfa'ce off the-button 30.

It willY be. seent from the foregoing that the present invention provides a practical and relatively inexpensive means for mounting an X-ray generating target of readily soluble metal, in substantially pure condition; on ai support.U of metal thatisreadily soluble with'4 the materialv of the target. They inventionwthus; teaches acommercially practical solution, for they problem of providing; X-ray-*generating targets: of pure germanium: and. other. readily soluble metals for; use; ingeneratorsffor. the production of X-rays l'raving4 predetermined, spectrahcharacteristics attendant-1 advantages; willbe fully under:-

stood from. thet'foregoing description;v and. it isr obvious thatV numerous: changes' may be. made' in` the form; construction. andi-arrangementr of the several parts without departing from.` the spirit or scope of. the4 invention, or sacrificing any of its. attendant'advantages, the form here-4 inf. disclosed: being a preferred." embodiment` forthe. .purpose of;demonstrating;ther-invention.

The-invention isfherebyl claimedzyas follows: An electron targetstructure: comprising abase element of. metal.. selected from; the classcome. prisingcopper, ironandnickel, readily soluble-l withgermanium, saldi base`v element having a target'end surface" formed: witlra'; cavity,v open ing outwardly.` atl' saidrv surface, a cup-shaped mounting' elementA of metal. selected' from the class' comprising' manganese; tungsten, and tantalum, dicultly soluble with germanium; saidf mounting element :being mounted 'iniV said 'cavity and integra-tedwith Ysaid base` element 'to formA alinerfonsaid cavity; andw-targetbutton of! germanium 'disposed within 'said cupeshaped li'ner and metallurgically*integrated therewith, where by saidi'button isphysicall'y integratedv withl and metallurgically isolated from said lbase element;

MICHAEL J. ZUNICKL REFERENCES CITED.

The following references'arefofrecord in the. file of this patent:

UNITED STATESJPA'I'ENTS.

OTHER. REFERENCES Y Terminology of Germanium, by-RZ- II Jafl'ee,v et'- al., Transactions: of their Electrochemical Society-:valla llgpm;

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